14 Verm . 
VUIKMKS. 
On Spirorbis carhonarius (pi. i. figs. 1 & 2) and Serpulites carhonarius 
(pi. i. fig. 3), see B. Etheridge, J. O. Soc. xxxiv. p. 9. 
Anatomy, Development, &c. 
Hatschek^s essay (42) may be divided into two parts, one of which deals 
with the development of Criodrilus and Folygordius. The ova of the former 
are contained in cocoons of large size for the Oligochcuta j the mesoderm 
is first represented by two large cells, which, though undergoing division, 
long remain at the posterior ends of the “ mesodermal stripes the name 
“^embryonic stripe ” is proposed for that of “ germ-stripe,*’ which has been 
very variously used ; segmentation commences in the mesoderm, and in 
the anterior region ; the cavity of the head is always primary, and is not 
formed by the cleavage of the mesodorm ; the setae are shown to be of 
mesodermal origin, and the history of the ‘‘ segmental organs ’* is carefully 
entered into ; these are not permanently represented in the first segment 
of the trunk, but a collection of cells was observed in it which appear to 
represent their rudiments. The larva of Polygordius is regarded as being 
the famous “Lovenian ” larva, and six stages of its development are 
described ; the cuticle is shown to bo greatly thickened in the region of 
the ciliated circlets, and to be traversed by pore-canals j the segments are 
developed in the mesoderm, and never appear in the other parts ; the 
development of the “ head-kidney ” is described, and the mid-gut alone of 
the portions of the enteric tract is of endodermal origin. The history of 
the generative organs is not given, but in the sixth stage there was 
observed a mass of rounded indifferent cells, which appear to be the rudi- 
ments of their products. 
Hatschek agrees with Ulianin in regarding Polygordius as an Annelid, 
and he looks upon Saccocirrus as standing between it and the more highly 
developed forms : the whole division is thus arranged : — 
I. Order. Polygordiidco {Archiannelides}. 
II. „ Chcetopodes. 
1st Suborder. Saccocirridce (Archichcetopodes). 
2nd „ Polychcstce. 
3rd ,, Oligochcetce. 
III. „ Hirudinea. 
IV. „ Gephyrei. 
In opposition to Semper the head is regarded as consisting of a single 
segment, characterized by the primary ccelom, oesophagus, and supra- 
oesophageal ganglia, and by the absence of the generative organs ; the 
question whether the Annelid form is colonial or consists typically of a 
head and a trunk segment which undergoes gemmation, is left undecided. 
The name of Trochophore is proposed for the larva of Polygordius, and 
the appearance of this as adult in the Rotatoria and as larval in the Mol- 
lusca is insisted upon ; and he regards all the Bilateria as having a 
relationship to a hypothetical Trochozoon of a somewhat similar character ; 
the Nemertinea are regarded as indicating their descent by the characters 
of the Pilidium larva, and the Gasterotricha, Nematodes (Vermes archi- 
coelomati), and Platodes (degenerate, V. accelomati) are considered to 
